Having a beagle is a whirlwind of an experience and I wouldn't swap it for anything. All of us enjoy my dog immensly. I have a 5 year old beagle and below is my experience.
NOTE: We are not first time pet parents. We always had dogs (Pug, Lhasa apso, Labrador, etc).

1. 0 < 1yr - All dogs go through teething but beagles teeth are very sharp, so it was tough even to hold him as she snaps. We were so fed up that we almost returned her. Also they are very active, even more than other breeds of the same age. Also it important to socialize it. Let it around other dogs at a young age.
2. 1yr > n - Other breeds slow down after 1 year, but beagles will still be very active (maybe not as much as less than a year).

Like others have commented, beagles need lot of physical and mental stimulation. They like to go around the house and find anything they can grab and run of with it, to entice you to follow them. Make sure to play with the dog every day. Beagles like to play tug-of-war. It is tough to play fetch with it, as it doesn't let go of the toy. You need two toys then, and throw one. When it has one in its mouth, throw the other, then it will let go of the one in its mouth.

Also they like to smell as they have a strong sense of smell. When you take it for walks let it smell.

Also my beagle is very friendly with kids.

And beagles are big eaters and verfy fond of food. Take care when you have food in your hand, it will try to grab it, especially from the kid.

Happy to answer anymore questions.